Semiconductor-metal hybrid heterostructures are promising building blocks for applications in catalytic, magnetic, and opto-electronic devices. The semiconductor's tunable band gap (300-4,000 nanometers 4.1-0.3 eV), broad and intense absorption (ε≈105-106 L-mol−1·cm−1), and long-lived exciton (up to 40 nanoseconds for CdSe, 1.8 microseconds for PbS) provide unmatched light absorption and emission capabilities. Of particular interest are large aspect ratio semiconductors, such as nanorods, due to their ability to generate multiple excitons. The metal can, depending on its nature serve as an additional chromophore, a fluorescence enhancer, a paramagnet, or even as a charge-collecting material where carriers localize after exciton quenching. For example, semiconductor-metal hybrid heterostructures have been shown to convert solar energy into potential and chemical energy. They become redox-active upon illumination and may remain redox-active after being stored in the dark for several hours. In addition, semiconductor and metal nanocrystals tend to display a higher degree of chemical-, photo-, and colloidal-stability (solubility) than other materials such as organic polymers and transition metal complexes.
Many of the documented photochemical deposition methods employ laser irradiation. Unfortunately, laser irradiation invariably occurs over small sample areas or spots, leading to low material yields and thus limiting its synthetic utility. Further, few researchers and even fewer synthetic chemists have direct and reliable access to expensive lasers.
Reliable and selective synthesis for these materials would increase their availability for both fundamental studies and applications. Further, reliable synthetic methods for fabricating semiconductor-metal hybrid heterostructures would increase the availability of these materials for their fundamental study and systematic testing, allowing for the establishment of structure-activity relationships and further facilitating their eventual application.
Embodiments of the invention provide such a method of fabricating semiconductor-metal hybrid heterostructures. These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.